GlossarySEO
What is mobile-first indexing?
Also called: mobile first indexing, mobile-first index
Definition
Mobile-first indexing means Google uses the mobile version of a page, crawled with its smartphone crawler, for indexing and ranking. If content is missing on mobile, Google doesn't see it.
Mobile-first indexing, explained
Google's documentation puts it in one line: Google uses the mobile version of a site's content, crawled with the smartphone agent, for indexing and ranking. The switch took years. Google's blog announced that after July 5, 2024, the small set of sites still crawled by desktop Googlebot would be crawled with Googlebot Smartphone, and that sites not accessible on mobile devices would no longer be indexed.
The practical rule is parity. Google's best practices say the mobile site should contain the same content as the desktop site. Layout can differ, and accordions or tabs are fine, but the text, headings, images and links should be there. The same applies to structured data, titles, meta descriptions, image alt text and robots meta tags. If your mobile template drops the comparison table or the FAQ to save space, that content effectively doesn't exist for Google.
Two warnings from the same guide. Google won't load content that requires user interactions like swiping, clicking or typing, so mobile-only "tap to load more" patterns can hide content. And image or video URLs that change on every page load can't be indexed properly.
Responsive design, one URL and one HTML document for all devices, avoids almost every mobile-first issue. Separate m. sites need matching content, correct canonical and alternate annotations, and the same robots rules on both versions.
Why it matters for founders
Founders design and check pages on laptops. Google judges the phone version. Anything you hide on mobile to keep it clean is also hidden from search.
Example
Your desktop pricing page shows a feature comparison table, but the mobile layout replaces it with a "See full comparison" button that loads it on tap. You render the table on mobile in a collapsible section instead.
Common mistakes
- Removing content from the mobile layout to save space.
- Loading mobile content only after a tap.
- Different structured data or meta tags on the mobile version.
- Testing SEO only on desktop.
Sources
- Google Search Central: Mobile-first indexing best practices
- Google Search Central Blog: Mobile indexing vLast (July 2024)
Checked
Related terms
- GooglebotGooglebot is Google's main web crawler for Search. It comes in a smartphone and a desktop version, and since mobile-first indexing most sites are crawled by Googlebot Smartphone.
- Viewport meta tagThe viewport meta tag,
<meta name="viewport" content="width=device-width, initial-scale=1">, tells mobile browsers to lay out the page at the device's width instead of a wide desktop canvas. - Lazy loadingLazy loading delays loading images, iframes or content until they're about to scroll into view. It speeds up pages, but content must load without clicks or scrolling or Google may never see it.
- Core Web VitalsCore Web Vitals are three Google metrics for real-user page experience: Largest Contentful Paint (loading), Interaction to Next Paint (responsiveness) and Cumulative Layout Shift (visual stability).